Hepatic ischemia-reperfusion (I/R) injury triggers release of small extracellular vesicles (sEVs) that can function as systemic conveyors of inflammatory signals. While sEV-mediated immune cell modulation has been studied extensively in vitro, knowledge is based largely on sEVs derived from cultured cells, rather than injured tissues. Consequently, the immunological impact of liver I/R-sEVs is poorly understood. Here, we combined in vitro and in vivo approaches with sEVs purified from mouse livers subjected to I/R to define their influence on dendritic cells (DCs). In vitro, in contrast to sham-sEVs, I/R-sEVs activated syngeneic bone marrow-derived DCs (BMDCs), inducing upregulation of costimulatory molecules and enhancing their capacity to stimulate naive allogeneic T-cells. In contrast, liver DCs (LDCs) were refractory to liver I/R-sEV-mediated activation. This differential responsiveness may in part reflect greater I/R-sEV internalization by BMDCs. To assess in vivo relevance, labeled sham or I/R-sEVs were administered intravenously. Following systemic delivery, syngeneic I/R-sEVs, but not sham-sEVs, accumulated in liver and spleen of otherwise naive mice exhibiting different patterns of uptake by immune cell populations. In the spleen, macrophages and B-cells were the principal I/R-sEV-acquiring populations, whereas in the liver, sEV uptake was dominated by macrophages and neutrophils. Additionally, while splenic DCs showed increased expression of activation markers and T-cell stimulatory activity following exposure to I/R-sEVs, LDCs were unresponsive. These findings identify liver-I/R-sEVs as promotors of extra-hepatic DC maturation/activation, whereas liver-resident DCs were refractory to I/R-sEV stimulation. The findings have implications for regulation of inflammatory responses following liver I/R injury.
Neutrophils have been implicated in mediating immune crosstalk between injured tissue and distal organs, either promoting local and distal inflammation or mediating tissue repair. Skin injury from ultraviolet (UV) light triggers neutrophil migration to the kidney, which may have implications for nephritis flares in systemic lupus erythematosus. Here, we demonstrate that after skin exposure to UV light, renal neutrophils upregulate proangiogenic transcriptional programs and activate renal endothelial angiogenesis and tissue remodeling processes in healthy kidneys. Ligand-receptor analysis identified Cd177-Pecam1 as a key neutrophil-endothelial interaction. In contrast to healthy control mice, skin exposure to UV light stimulated the expression of Tgfβ and Wnt signaling pathways in lupus-prone MRL/lpr mice. This tissue remodeling response was neutrophil dependent. Spatial transcriptomic analysis of lupus nephritis kidneys revealed that tissue remodeling and profibrotic pathways are highly expressed in neutrophil-rich areas. Neutrophil intrarenal levels were higher in the kidneys of lupus nephritis patients with active skin disease, compared with those without skin involvement at the time of the nephritis flare. Moreover, urinary neutrophils were increased in systemic lupus erythematosus patients with active skin disease, including sun-associated skin rash, even in the absence of lupus nephritis. These results support a model in which UV-triggered skin injury activates a neutrophil-mediated skin-kidney axis that promotes differential tissue remodeling pathways in healthy compared with lupus-prone kidneys.
Through screening of a VHH phage display library constructed from an alpaca immunized with the recombinantly expressed murine myelin oligodendrocyte (MOG)-specific 2D2 T cell receptor (TCR), we identified nanobodies that reduced antigen-driven 2D2 T cell activation in vitro. Immunoblotting and staining confirmed TCRβ chain reactivity and Vβ11-associated recognition in polyclonal T cell populations. Site-specific sortase-mediated conjugation with desferrioxamine and 89Zr enabled nanobody-based immuno-PET/CT. In vivo imaging showed tracer accumulation in secondary lymphoid organs in settings enriched for Vβ11-expressing 2D2 T cells. In mice symptomatic for experimental autoimmune encephalomyelitis that had received MOG-specific 2D2 T cells, we observed a spinal cord-associated signal. This corresponded to accumulation of transferred Vβ11-expressing 2D2 T cells within inflamed spinal cord tissue. Compared with full-length immunoglobulins and multimeric peptide-MHC reagents that primarily support ex vivo detection of antigen-specific T cells, TCR-specific nanobodies show rapid clearance and improved tissue penetration that favor high-contrast immuno-PET/CT imaging of defined T cell populations in vivo.
The human T cell receptor (TCR) repertoire is generated in the thymus through a process of recombination involving two gene loci, TRA and TRB, and the pairing of the resulting peptide chains. Because of the lack of allelic exclusion in TRA loci, it is possible for a T cell to express either one or two distinct TRA chains, and although both configurations are present in significant quantities in the mature T-cell population, this has been viewed a largely inconsequential phenomenon. We analyzed human TRA repertoires using sequencing of genomic DNA as starting material from T-cell subsets representing different maturation stages of T cells, from donors aged from 7 d to 61 yr, some with chronic exposure to pathogen or autoimmune antigens. The frequency of productive TRA clonotypes increased along the T cell maturation stage and showed a consistent positive correlation with the donor age. Moreover, our data provide evidence of chronic antigen exposure further increasing the frequency of productive TRA sequences. We propose that these unexpected findings are due to a preferred positive peripheral selection of the T cell population bearing 2 functional TRA chains.
Antibody-secreting cells (ASCs) are critical effectors of humoral immunity, wherein their distinct isotypes play specialized roles in pathogen defense. Despite studies defining the transcriptional programs of selected ASC isotypes, specific mechanisms underlying isotype-specific gene regulation are largely unaddressed. Here, we performed an integrated multiomics analysis (RNA sequencing, ATAC-seq [assay for transposase-accessible chromatin using sequencing], DNA methylation) on surface-sorted IgM, IgG, and IgA ASCs isolated from the spleens and mediastinal lymph nodes of mice following influenza infection. Although conclusions regarding temporal and spatial specific programs could not be determined, we observed isotype-enriched expression patterns mapping to TLR signaling, cell cycle, cholesterol metabolism, cell adhesion, and homing. ETS:IRF, NFAT, REL, RUNX, SMAD, and STAT5 binding motifs differentially mapped to isotype-enriched gene expression programs. Additionally, DNA hypomethylation patterns in class-switched ASCs correlate with transcription factor-specific programming. The unique transcriptional and epigenetic programs among the 3 ASC isotypes suggest that each is a distinct lineage that dictates isotype-specific functional characteristics important for humoral immunity.
Sepsis-induced cardiac dysfunction is a primary contributor to mortality, and microRNAs (miRNAs) are recognized as crucial mediators in sepsis pathogenesis. This study aims to identify the key regulatory miRNAs involved in cardiac dysfunction stemming from sepsis. We developed a rat model of sepsis using cecal ligation and puncture (CLP). Myocardial tissue from these rats underwent miRNA sequencing and transcriptome sequencing. Echocardiography was utilized to assess heart function, while cardiac damage was evaluated through HE staining, analysis of inflammatory factors, and detection of tissue injury biomarkers. To model inflammation-induced cardiomyocyte injury, rat cardiomyocyte H9C2 cells were treated with lipopolysaccharide (LPS). Cellular viability was determined using CCK8, and apoptosis was assessed via TUNEL staining and flow cytometry. Oxidative stress levels were analyzed by flow cytometry, and related marker levels were quantified by ELISA. Our results demonstrated that the CLP group displayed substantial cardiac dysfunction, myocardial injury, and elevated inflammatory factor levels. MiR-221-5p was found to be upregulated in both the in vivo and in vitro models. Overexpression of miR-221-5p reduced cardiomyocyte survival while increased apoptotic activity and oxidative stress in LPS-stimulated H9C2 cell. Mechanistically, Neuropilin-1 (NRP1) was identified as a target of miR-221-5p. The cardioprotective effect of miR-221-5p inhibition was reversed by NRP1 knockdown. Furthermore, in vivo administration of a miR-221-5p antagomir mitigated cardiac dysfunction and myocardial damage associated with septic conditions. In conclusion, our findings indicate that miR-221-5p exacerbates septic cardiomyopathy by negatively regulating NRP1, suggesting that the miR-221-5p/NRP1 pathway could represent a novel therapeutic strategy for sepsis-related heart complications.
Systemic sclerosis (SSc) is an autoimmune condition affecting several organs. It is identified by thickening of the dermis, connective tissue affected by collagen accumulation, and vascular injuries that induce hypoxia. The present study aimed to determine whether extracellular vesicles (EVs) from adipose-derived stem cells (ADSCs) attenuated bleomycin-induced skin fibrosis and oxidative stress in scleroderma. ADSCs and their EVs were separated and a bleomycin-induced SSc mouse model was constructed. High-throughput sequencing was employed to study abnormal expression of circular RNAs in SSc skin tissues with or without ADSC-EV treatment. The regulatory mechanism and targets were studied using bioinformatics analysis, luciferase reporting analysis, angiogenic differentiation experiments, and RT-qPCR detection analysis. EVs from ADSCs were successfully isolated. The exosome treatment prevented dermal thickening and fibrosis in bleomycin-induced scleroderma. In addition, circ-Zfyve9 was demonstrated to have an important function in ADSC-EV-mediated skin tissue protection. GPX4 and miR-135 were shown to be downstream targets of circ-Zfyve9. Overexpressing miR-135 or downregulating GPX4 reversed the promotion effects of circ-Zfyve9 on angiopoiesis by increasing lipidosome ROS in EPCs under hypoxic conditions. Overexpressing miR-135 or downregulating GPX4 reversed the inhibition effect of circ-Zfyve9 on fibrosis in myofibroblasts under hypoxic conditions. Overexpressing circ-Zfyve9 increased the therapeutic effect of ADSC-EVs. EVs from ADSCs attenuated bleomycin-induced skin fibrosis and oxidative stress in scleroderma via circ-Zfyve9 delivery.
Sex differences exist in the immune responses to infections and in the prevalence and severity of autoimmune and allergic diseases. These sex differences may be caused by sex hormones and/or variable inactivation of X chromosome genes. The 4 core genotypes mice allow for distinction between the effects of sex hormones and chromosomes on physiology and disease pathology. In the FCG mouse model, the Sry gene is deleted from the Y chromosome and inserted into chromosome 3 as multiple copies of a transgene, allowing for phenotypic male and female mice with XX and XY chromosomes. We sought to investigate the role of sex hormones and chromosomes in respiratory syncytial virus infection and allergen-induced airway inflammation. However, in performing these studies, we found that the immune response in FCG males (XXM and XYM) was significantly blunted. XXF and XYF had 4-fold more CD3+CD4+ T cells and over 7-fold more CD3+CD8+ T cells compared to XXM and XYM in the lungs following stimulus. CD4+ and CD8+ T cells were also significantly decreased in XXM and XYM mice in the lungs, spleen, and peripheral blood at baseline with no effect on B cells, NK cells, or myeloid cells. Thymic T cell numbers were similar among groups, and bone marrow progenitors were unchanged between groups. Overall, the translocation of Sry to chromosome 3 resulted in dramatically decreased immune responses to RSV infection and allergen-challenge, indicating that FCG male mice do not mount appropriate immune responses to a respiratory virus infection.
Mucosal-associated invariant T (MAIT) cells express a semi-invariant T cell receptor (TCR) that recognizes bacterial-derived antigens presented on MR1. Upon TCR triggering, MAIT cells respond rapidly, producing a range of effector molecules which facilitate host-protective responses in the context of microbial infections. In contrast, MAIT cell responses to viral infection are instead triggered by the recognition of cytokines, and occur independently of TCR engagement. The molecular and metabolic regulation of MAIT cell TCR responses is rapidly emerging, but there is a paucity of data on cytokine driven responses. Here, using high-resolution, quantitative proteomic analysis, we map the downstream proteome of innate cytokine (IL-18/IFNα)-activated MAIT cells, highlighting robust cytokine-driven remodeling and a signature that is distinct from the TCR-driven response. MAIT cells significantly increase protein biosynthesis in response to innate cytokine stimulation and rapidly upregulate the production of IFNγ, granzyme B, and IFN-stimulated gene 15. We demonstrate the metabolic kinetics of MAIT cell responses to cytokine stimulation and highlight a rapid but transient glycolytic burst that is uncoupled from mitochondrial remodeling and contrasts the robust metabolic profile elicited downstream of TCR engagement. Finally, we demonstrate differential contributions from both glycogen and glucose in supporting MAIT cell responses to innate cytokines and further highlight the importance of nutrient availability as a governing signal for MAIT cell fitness and effector functioning.
Lysosomes drive antigen proteolysis and peptide loading for major histocompatibility complex class II (MHCII) presentation in antigen-presenting cells (APCs), enabling activation of peptide-specific CD4+ T helper cells (CD4+ Th cells). Tight regulation of endocytic trafficking, protease activity, and peptide editing is required to generate stable peptide-MHCII complexes and balanced immune responses. Conversely, dysregulation of antigen catabolism or loading can promote impaired pathological immunity, including autoimmunity. However, key mechanistic questions remain, including how proteolysis, redox regulation, and peptide editing shape the MHCII ligandome across APC subsets and inflammatory states. In this review, we explore the main mechanisms of antigen acquisition, endocytic/lysosomal factors controlling MHCII-restricted processing and presentation, and evidence linking lysosomal dysfunction to autoimmunity. Understanding the functions of lysosomes in immune cells is crucial for elucidating their roles in physiological and pathological states, for developing targeted therapeutic strategies and for enhancing the safety and efficacy of novel biological entities (NBEs).
Healthy aging relies on the maintenance of a diverse T cell pool. This diversity is ensured by balancing thymic output, differentiation of naive into memory T cells, T cell proliferation and cell death. For naive T cells, the balance of these processes differs between standard laboratory mice and humans. This may be a true species difference or, alternatively, result from the vastly different amounts of antigens to which standard laboratory mice and humans are exposed. Using wildlings, that is, laboratory mice born to wild mice, we studied the impact of antigen-exposure through a natural microbiome on naive and memory T cell maintenance. We found that standard laboratory mice and wildlings maintain their naive T cell pools similarly: naive T cells rarely divide and are replaced by thymic emigrants at similar rates. The daily replacement rate of memory T cells, on the other hand, is about 50% faster in wildlings than in standard laboratory mice. In both types of mice, about 20% of newly produced memory T cells originate from recruitment of naive T cells, while the remaining cells are produced by their clonal expansion and by self-renewal. In older mice, this drops to 5%. In humans, a similarly large fraction of memory cells originate from recruitment of naive T cells. Unlike in mice, most naive T cells in human adults are formed by naive T cell proliferation. Thus, while both types of mice mimic the maintenance mechanisms of the memory T cell pool in humans, even wildlings fall short as a model for human naive T cell maintenance.
NK cells are classically defined by their rapid cytotoxicity against tumor cells and infected cells and by early inflammatory cytokine production. However, unconventional roles for NK cells as regulators of immunity and tissue homeostasis have recently been uncovered. Beyond their classical roles, NK cells can orchestrate leukocyte trafficking, curtail responses of other immune cells, remove protein aggregates, support pregnancy, and contribute to healthy tissue regeneration. We discuss the importance of these myriad functional activities of NK cells in infection, cancer, autoimmunity, atopic and allergic disease, pregnancy, tissue injury, and neurodegenerative diseases. The functional pleiotropy of NK cells provides new avenues of translational utility for these innate lymphocytes and represents an unexplored complexity in conventional clinical applications of NK cells against infection and cancer.
In the established model of classical trained immunity, metabolic and epigenetic hubs serve as central integrators of innate memory. While typically associated with proinflammatory reprogramming, the regulation of autophagy and cellular proteostasis remains essential for guiding macrophage differentiation and ensuring efficient pathogen clearance without excessive inflammation. In this study, we demonstrate that sodium butyrate (SB), a short-chain fatty acid, induces a functional profile that diverges from the canonical pathways observed in classical innate immune training. The induction of an innate reprogrammed state in chicken macrophages by SB is strictly dependent on the cellular developmental stage, occurring only during the early stages of differentiation from chicken bone marrow-derived macrophages but not in fully differentiated cells. This suggests that SB primarily facilitates an innate immune reprogramming with a specific temporal window of sensitivity. Our results show that SB-reprogrammed chicken macrophages exhibit enhanced reactive oxygen species generation, altered cytokine expression, and an increased capacity to kill a diverse range of bacteria. Treatment with chemical inhibitors further demonstrated that these heightened antibacterial effects are directly attributed to increased reactive oxygen species production and autophagy. In summary, these findings indicate that SB induces functional outcomes distinct from classical trained immunity and can elicit innate immune memory through alternative regulatory axes. Our data suggest that distinct innate reprogramming states give rise to alternative activation programs and that innate immune memory exists along a spectrum of phenotypes rather than as a single, uniform state.
B-cell responses rely on a tightly coordinated interplay between transcriptional programs and metabolic reprogramming. Upon activation, B cells remodel their metabolic profiles, with enhanced glutamine metabolism supporting biomass synthesis and proliferation. However, whether and how glutaminolysis underpins B-cell responses in early vertebrates remains largely unexplored. Here, using the Nile tilapia (Oreochromis niloticus) as a model, we demonstrate that IgM+ B cells markedly increase glutamine utilization upon activation. Glutamine deprivation impaired B-cell activation and proliferation, whereas glutamine supplementation promoted these processes. During Edwardsiella piscicida infection, pharmacological inhibition of glutamine metabolism significantly reduced the expansion of IgM+ B cells and compromised antibody secretion. Mechanistically, glutamine metabolism in tilapia IgM+ B cells was governed by the transcription factor c-Myc. Inhibition of c-Myc disrupted glutaminolysis, leading to diminished B-cell proliferation and antibody production. Upon activation, IgM+ B cells coordinated c-Myc expression and downstream glutamine metabolism through the mTORC1 and ERK signaling pathways, thereby coordinating metabolic and immune functions. Notably, this regulatory mechanism operated in a B cell-intrinsic manner and was independent of T-cell help. Collectively, our findings reveal that teleost B cells possess evolutionarily conserved and sophisticated immunometabolic regulatory programs. This study provides new insights into how metabolic pathways are integrated with immune signaling to control B-cell function, highlighting coordinated immunometabolic regulation as a fundamental mechanism underlying vertebrate B-cell immunity.
Osteoarthritis (OA), the most prevalent degenerative joint disease, leads to significant disability in the elderly and is characterized by functional and structural deterioration of the knee joint. This study aimed to investigate the therapeutic potential of skullcapflavone II (SkII), a flavonoid known for its anti-inflammatory properties, in the context of OA. Our results demonstrated that SkII markedly suppressed IL-1β-induced extracellular matrix degradation and apoptosis in chondrocytes. Furthermore, SkII reduced reactive oxygen species and malondialdehyde levels while enhancing superoxide dismutase activity and the glutathione/glutathione disulfide ratio. SkII also upregulated the expression of SLC7A11 and glutathione peroxidase 4 (GPX4). Mechanistic investigations revealed that SkII, similar to the ferroptosis inhibitor ferrostatin-1, effectively counteracted erastin-induced apoptosis and extracellular matrix degradation. Both SkII and ferrostatin-1 promoted SLC7A11 and GPX4 expression at transcriptional and protein levels and diminished ferrous ion (Fe2+) accumulation in chondrocytes. In vivo experiments confirmed that SkII treatment attenuated ferroptosis in OA rats by activating the SLC7A11/GPX4 pathway. In conclusion, our findings indicate that SkII alleviates OA progression by inhibiting ferroptosis through the SLC7A11/GPX4 signaling axis. These results underscore the potential of SkII as a promising therapeutic candidate for the treatment and prevention of OA.
The immune system initially protects hosts against viral pathogens, with chemokines guiding immune cell movement. However, their expression patterns and immune cell recruitment mechanisms during transmissible gastroenteritis virus (TGEV) infection are still not fully understood. Here, we identified a distinct chemokine expression profile in intestinal epithelial cells following TGEV infection. Among these, CXCL10 selectively induced the chemotaxis of CD4+ CXCR3+ T cells, while only modestly recruiting CD8+ CXCR3+ (Tc1) T cells and showing minimal involvement in B cell recruitment, thereby shaping the intestinal immune microenvironment to promote TGEV infection. CXCL10 can also upregulate the expression of its receptor CXCR3, thereby further potentiating the migration of CD4+ T cells to the infected region. During this process, CXCL10 activated the CXCR3-Rho GTPase-cofilin signaling axis, driving actin cytoskeletal remodeling. Through this process, CD4+ T cells are channeled from the lamina propria to the infected intestinal lining, facilitating their functional responses. Collectively, these findings reveal a novel mechanism underlying Th1 cell trafficking during TGEV infection and suggest objectives for therapeutic vaccine creation and disease management.
COVID-19 continues to present ongoing global health challenges driven by diverse immune responses and heterogeneous clinical outcomes. The ACCORD trial evaluated 3 investigational treatments-bemcentinib, tozorakimab, and zilucoplan-in patients hospitalized with COVID-19, each of which has demonstrated clinical efficacy. To better understand their molecular mechanisms, we conducted a mechanistic follow-up study, integrating transcriptomic and clinical data from 65 patients and applying cellular deconvolution, differential expression, coexpression, and pathway enrichment analyses to uncover treatment-specific immune responses. Each therapy induced transcriptional shifts and modulated distinct immune pathways implicated in severe disease. Bemcentinib primarily modulated myeloid cell populations and inflammatory signalling; zilucoplan enhanced B-cell signalling and lymphocyte-associated pathways; and tozorakimab exerted broad immune and cellular responses across immune cell types. Co-expression analysis revealed gene networks associated with clinical improvement, each driven by distinct treatment-specific hub genes, indicating diverse regulatory mechanisms across treatments. Improved outcomes correlated with gene expression shifts in 4 key immunological pathways: B-cell signalling, antiviral defense, innate inflammation, and platelet/coagulation activity. In contrast, nonresponders had persistent dysregulation of 1 or more of these gene signatures. Our findings define molecular signatures of treatment response and failure in COVID-19, providing mechanistic insight into how distinct therapies modulate the immune system. These insights support the need for adaptive precision medicine approaches tailored to individual, evolving immune trajectories. Moreover, the immunological mechanisms targeted by these repurposed immunomodulatory therapies may inform treatment strategies across a broader spectrum of immune-mediated diseases beyond COVID-19.
Tuberculosis (TB) remains one of the leading causes of death from a single infectious agent worldwide, yet the host pathways that regulate antigen presentation and lung inflammation during Mycobacterium tuberculosis (Mtb) infection are incompletely defined. Sorting nexin 5 (SNX5) is a protein implicated in endosomal trafficking, antigen processing, and antiviral host defense, but its contribution to antibacterial immunity is unknown. Here, we show that SNX5-deficient mice exhibit increased mortality following low-dose aerosol Mtb infection despite unchanged pulmonary bacterial burden compared with wild-type mice. Snx5-/- mice developed exacerbated lung inflammation without major alterations in immune cell recruitment. In macrophages, Snx5 did not affect phagocytosis, vacuolar maturation, intracellular bacterial control, or global transcriptional responses to Mtb but was required for efficient major histocompatibility complex (MHC) class II antigen presentation. Snx5 deficiency was associated with reduced endolysosomal proteolysis and impaired MHC class II antigen presentation in vitro, resulting in reduced activation of antigen-specific CD4+ T cells without altering surface MHC class II abundance or costimulatory molecule expression. Together, these findings identify SNX5 as a regulator of MHC class II antigen presentation that influences inflammatory outcomes during pulmonary Mtb infection.
There is substantial interest in developing novel engineering strategies to promote the sustained metabolic fitness of therapeutic T cells. We previously showed that overexpression of RAS homologue enriched in brain (RHEB), a positive regulator of mammalian target of rapamycin complex 1 (mTORC1), promotes aerobic glycolysis and increases the anti-tumor functions of effector CD8+ T cells. To address whether these effects are conserved in CD4+ T cells, we have now examined how enforced activation of mTORC1 activity affects CD4+ T cell differentiation and function. Rheb overexpression induced a more balanced metabolic shift in CD4+ T cells than in CD8+ T cells, with increases in both oxidative phosphorylation and aerobic glycolysis. Although Rheb overexpression initially increased CD4+ T cell activation and proliferation in vitro, the underlying population architecture was complex, involving a shift to both more proliferative, cytotoxic-like cell states as well as more quiescent cell clusters characterised by counter-regulation of mTORC1 activity. Following adoptive transfer, tumor antigen-specific Rheb-transduced CD4+ T cells showed greater persistence but were less efficient than controls in eliminating tumor. This functional deficiency could be explained by a greater propensity of persisting Rheb-transduced CD4+ T cells to develop features of immune exhaustion, as evidenced by expression of multiple co-inhibitory receptors and impaired proliferation upon tumor rechallenge. Together, these data demonstrate the dynamic population response to tuning of T cell mTORC1 and the need to separately appraise cellular outputs of therapeutic CD4+ versus CD8+ T cells when metabolic pathways are manipulated by the same method.
Golden hamster (Mesocricetus auratus) and ferret (Mustela putorius furo) are important animal models in studies of human infectious disease. They are used widely to investigate pathogen-spreading mechanisms and host immunology to evaluate the safety and efficacy of small molecules, biologic drugs and vaccines. To this end, immunoglobulin A (IgA) and its Fcα receptor (FcαR) play critical roles in humans but are not well characterized in these 2 species. Golden hamster and ferret IgA and FcαR were recombinantly expressed, purified, and characterized for N-linked glycosylation site occupancy and binding affinity. Based on sequence and structural alignments, hamster IgA showed greater similarity to human IgA than did ferret, and hinge domains in both small animal models suggested greater structural homology to human IgA2 than IgA1. Despite considerable sequence divergence in both immunoglobulins and receptors, and the lack of binding between ferret FcαR and ferret IgA, human IgA bound to both hamster and ferret FcαR with high affinity. Further, differences in dissociation rates were dependent on test format, suggesting that the 2:1 stoichiometry of human FcαR: IgA is recapitulated in these animals. Overall, this work suggests the suitability of these animals to model protection or pathology driven by interactions between human IgA and host FcαR and will aid in critical and confident interpretation of infection and immunization studies in each species.
